using Connected.Annotations;
using Connected.Configuration;
using Connected.Data.Sharding;
using Connected.Data.Sql;
using Connected.Entities;
using Connected.Entities.Annotations;
using Connected.Entities.Storage;
using Connected.Middleware;

namespace Connected.Data.Schema.Sql;

internal enum ConstraintNameType
{
	Index = 1,
	PrimaryKey = 2,
	Default = 3
}

[Priority(0)]
internal sealed class SqlSchemaMiddleware : MiddlewareComponent, ISchemaMiddleware
{
	public SqlSchemaMiddleware(IMiddlewareService middleware, IStorageProvider storage, IConfigurationService configuration)
	{
		Middleware = middleware;
		Storage = storage;
		Configuration = configuration;
	}

	private IMiddlewareService Middleware { get; }
	private IStorageProvider Storage { get; }
	public IConfigurationService Configuration { get; }

	public Type ConnectionType => typeof(SqlDataConnection);

	public string DefaultConnectionString => Configuration.Storage.Databases.DefaultConnectionString;

	public async Task<bool> IsEntitySupported(Type entityType)
	{
		await Task.CompletedTask;
		/*
		 * By default, all entities are supported by this middleware.
		 */
		return entityType.IsAssignableTo(typeof(IEntity));
	}

	public async Task Synchronize(Type entity, ISchema schema)
	{
		await Synchronize(schema, DefaultConnectionString);
		/*
		 * First query all sharding middleware because we must perform synchronization
		 * on all nodes.
		 */
		if (await ResolveShardingMiddleware(entity) is IShardingMiddleware sharding)
		{
			foreach (var node in await sharding.ProvideNodes(entity))
				await Synchronize(schema, node.ConnectionString);
		}
	}

	private async Task Synchronize(ISchema schema, string connectionString)
	{
		var args = new SchemaExecutionContext(Storage, schema, connectionString);
		/*
		 * Sinchronize schema object first.
		 */
		await new SchemaSynchronize().Execute(args);
		/*
		 * Only tables are supported
		 */
		if (string.IsNullOrWhiteSpace(schema.Type) || string.Equals(schema.Type, SchemaAttribute.SchemaTypeTable, StringComparison.OrdinalIgnoreCase))
			await new TableSynchronize().Execute(args);
	}

	private async Task<IShardingMiddleware?> ResolveShardingMiddleware(Type entityType)
	{
		var all = await Middleware.Query<IShardingMiddleware>();

		foreach (var middleware in all)
		{
			if (middleware.SupportsEntity(entityType))
				return middleware;
		}

		return null;
	}
}